Apparatus for forming thread rolling dies



H. N. FOX

March 11, 1989 APPARATUS FOR FORMING THREAD ROLLING DIES Filed June 7, 1965 INVENTOR.

Awe/9y 11/ Fax March 11,1969 I H; wQFox APPARATUS FOR FORMING THREAD ROLLING DI ES v v Sheet 3- of 6 "Filed June 7, 1965 70 954;: caea /v BY MwsA/A/K MIPPM/G ,4 rrazwav;

H. W. FOX

March 11, '1969 APPARATUS FOR FORMING THREAD ROLLING DIES Sheet Filed June 7, 1965 WWW-E- LAu.

March 11, 1969 H. w. FOX 3,431,680

APPARATUS FOR FORMING THREAD ROLLING DIES Filed June 7, 1966 Sheet 4 of 6 H. W. FOX

March 11, 1969 APPARATUS FOR FORMING THREAD ROLLING DIES Sheet Filed June 7, 1965 March 11, 1969 H. w. FOX 3,431,680

APPARATUS FOR FORMING THREAD ROLLING DIES Filed June 7, 1965 Sheet of 6 INVENTOR.

x/fliey M 0% I'TOIPA/EVG United States Patent 3,431,680 APPARATUS FOR FORMING THREAD ROLLING DIES Harry W. Fox, Cleveland, Ohio, assignor to Pratt & Whitney, Inc., Cleveland, Ohio, a corporation of Delaware Filed June 7, 1965, Ser. No. 461,640 US. Cl. 51-94 11 Claims Int. Cl. 32% 47/02; B23c 3/28, 3/32 ABSTRACT OF THE DISCLOSURE Apparatus for forming thread rolling dies having curved relief portions on the ends which blend into the central section along a line perpendicular to the longitudinal axis of the die block. The apparatus incorporates a work holding device provided with a base plate rigidly mounted on the reciprocating carriage of a grinding machine. A lift plate is mounted on the base plate by a first carn means operable to raise one end or the other of the lift plate in response to the reciprocation of the carriage. An indexing plate is pivoted on the lift plate so that it can be rotatably indexed about a vertical axis to the desired helix angle. A tipping cradle is mounted on the indexing plate by a second cam means operable to laterally tip the cradle in timed relation to the operation of the first cam means.

This invention relates generally to the manufacture of thread rolling die blocks and more particularly to a novel and improved thread rolling die block and to a novel and improved method and apparatus for forming such die blocks.

Reciprocating die blocks can be used to roll form high quality threads on bolts, cap screws, or the like, if curved relief portions are provided at the ends of at least one of the die blocks to prevent the sudden application or release of the thread rolling pressures. The relief at one end of the block is referred to as the roll-on portion and the relief at the other end is referred to as the rolloff portion. Between the end reliefs the die block has a planar central section usually formed long enough to provide at least three complete turns of the blank being threaded.

The thread forming lands on a die block are inclined relative to the longitudinal axis of the block by an angle equal to the helix angle of the thread to be rolled. However, the bolt blank rolls along an axis perpendicular to the longitudinal axis of the die block so the roll-on and roll-01f reliefs must be blend into the central section along a line perpendicular to the longitudinal axis of the die block if canting or tilting of the blank is to be avoided. Canting or tilting of the blank results if the application or the release of the rolling pressure is not uniform along the length of the shank of the blank.

Thread rolling die blocks are generally formed in grinders, such as crush grinders, having a grinding wheel 'With its peripheral surface shaped to accurately form the tooth lands in the block of die steel. The die block is moved under the Wheel in a direction parallel to the tooth lands. Therefore, the line of movement of the die block under the wheel is inclined relative to the longitudinal axis of the block by an angle equal to the helix angle.

In the past, various methods of automatically forming the roll-0n and roll-off reliefs at the end of the die block have been attempted but none have produced satisfactory results. One such method provided for the lifting of the ends of the block as it passed under the grinding wheel, but this was unsatisfactory since the relief formed blended into the central section along a line perpendicular to the tooth lands and not perpendicular to the longitudinal axis of the die block. Therefore, tipping or cantin'g of the bolt blank occurred and produced difliculties, particularly at the roll-on portion where a pusher advances the bolt blank between the thread rolling dies. If the rollon is not perpendicular to the longitudinal axis of the bolt blank enters the dies tilted or canted which creates difliculties in alignment of the threads. This produces an end product which will not gauge or pass inspection.

Heretofore no satisfactory machine has been available to automatically form the roll-on and roll-off relief so it has been necessary to hand grind or hand file these reliefs. Such hand methods have obvious disadvantages of high cost and nonuniform results.

A die block and a machine for its manufacture incorporating this invention permits the automatic manufacture of the central section and both of the end reliefs. The roll-0n and roll-off reliefs produced blend into the central section along a line substantially perpendicular to the longitudinal center line of the block. Because automatic means are used to produce the entire thread rolling surface, including the end reliefs, the labor costs are minimized and the resulting die blanks have a high degree of accuracy.

In the illustrated machine incorporating this invention the die block is supported on the reciprocating carriage of the machine by a cam operated fixture which utilizes the reciprocating movement of the carriage to operate the cam drives. Two separate movements are compounded to produce the roll-on and roll-off reliefs and these sepa rate movements are automatically synchronized to produce the desired result. One movement is the vertical lifting or lowering of the ends of the die block as they pass under the grinding Wheel and the other movement, which is synchronized with the vertical movement, causes a tilting of the die block along its central longitudinal axis at the upper surface of the die block. The raising of the die block ends and the tipping of the die block are synchronized so that the end reliefs blend into the planar central section along a zone or line substantially perpendicular to the longitudinal axis of the die block. This compound movement is produced automatically by cams so operator skill is minimized and uniformly high quality die blocks are produced.

The illustrated machine and fixture includes the grinding wheel rotating about a horizontal axis in a plane perpendicular to the plane of movement of the reciprocating carriage of the machine. The fixture includes a base plate rigidly mounted on the reciprocating carriage. A lift plate is mounted on the base plate so that cam means operate to raise one end or the other end of the lift plate at predetermined points in the cycle. An indexing plate is pivoted on the lift plate so that it can be indexed relative to the lift plate to the desired helix angle. Mounted on the indexing plate is a tipping cradle which is cam operated to provide lateral tipping of the assembly about a longitudinal axis in response to movement of the reciprocating carriage relative to cams mounted on the machine frame. The pivot structure for the cradle is arranged so that the axis of tipping extends along the central longitudinal axis of the upper surface of the die block.

It is an important object of this invention to provide a novel and improved machine for automatically forming thread rolling die blocks having roll-on and roll-off reliefs which are symmetrical with respect to the central longitudinal axis of the die block.

It is another important object of this invention to provide a novel and improved machine for automatically grinding thread rolling die blocks having roll-on and rolloff portions which smoothly blend into the central rolling portion of the die block along a line substantially perpendicular to the central longitudinal axis of the die block.

It is another important object of this invention to provide a novel and improved fixture including cam operated means to raise the end of a thread rolling die block as the ends pass under the grinding wheel and at the same time tip the die block about a horizontal axis located substantially at the upper surface of the die block to automatically form the roll-on and roll-off reliefs.

It is still another object of this invention to provide a novel and improved machine for forming thread rolling die blocks which includes means to adjust the helix angle, means to raise the ends of the die block at predetermined points in the stroke of the machine and means to tip the die block about a central longitudinal axis thereof.

It is still another object of this invention to provide a novel and improved die block formed by a contoured grinding wheel wherein end reliefs are formed by raising the ends of the die block while tipping the die block about its central longitudinal axis substantially in the plane of the upper surface thereof.

It is still another object of this invention to provide a novel and improved thread rolling die block having rollon and roll-off reliefs at its ends generated by raising and simultaneously tipping the die block with respect to a contoured grinding wheel so that the reliefs are substantially symmetrical with respect to the central longitudinal axis of the die block.

It is still another object of this invention to provide a novel and improved fixture for use with form cutters or grinders having a reciprocating carriage wherein the fixture includes cam operated means to raise the ends of the fixture at predetermined points in the reciprocating cycle of the carriage and cam operated means to tip the carriage in a manner timed with the raising thereof to generate contoured sections along the length of a workpiece supported by the fixture.

Further objects and advantages will appear from the following description and drawings wherein:

FIGURE 1 is a perspective view of a thread rolling die block incorporating this invention formed with the machine and fixture illustrated in FIGURE 2;

FIGURE 2 is a perspective view of a preferred fixture incorporating this invention mounted on a crush grinder;

FIGURE 3 is a plan view of the fixture illustrated in FIGURE 2 illustrating the indexing movement for setting the helix angle of the thread lands;

FIGURE 4 is a side elevation of the fixture partially in section;

FIGURE 5 is a cross-section of the fixture illustrating the structural detail of the lift plate support and the cam mechanism for raising the ends thereof;

FIGURE 6 is a side elevation of one of the support links connecting the lift plate with the eccentric shafts;

FIGURE 7 is a fragmentary section illustrating the central drive bearing and pin which axially locates the lift plate of the fixture with respect to the fixture base and also illustrating the pivot bearing for the indexing movement;

FIGURE 8 is a fragmentary view of the cams and cam followers which rotate the eccentric shafts and raise and lower the ends of the lift plate;

FIGURE 9 is a cross-section illustrating the support for the cradle which permits tipping about a central longitudinal axis along the upper surface of the die block.

FIGURE 10 is a fragmentary section taken along 10-10 of FIGURE 9 illustrating the upper roller of the tilting cradle support;

FIGURE 11 is a fragmentary section taken along 11-11 of FIGURE 9 illustrating the structural detail of the end thrust rollers of the cradle support; and,

FIGURE 12 is a fragmentary section taken along 1212 of FIGURE 9, illustrating the sturctural detail of the lower rollers of the cradle support structure.

Referring to FIGURE 2, a fixture incorporating the present invention is illustrated with a crush grinder having a bed frame 10 and a profiled cutting wheel 11 journaled on the bed frame 10 for rotation around a horizontal axis 12 contained in a vertical plane perpendicular to the longitudinal axis of the bed frame 10. A carriage 13 is reciprocable on the bed frame in a horizontal direction indicated by the arrow 14.

A thread rolling die block 16 is mounted on a magnetic chuck 17 which is in turn mounted on a cam operated fixture designated in its entirety by 18. The fixture 18 is provided with a base plate 19 secured to the carriage 13 by clamping arms 21 so that the base plate 19 is carried back and forth in the direction 14 by the carriage 13 during the reciprocation of the carriage.

A lift plate 22 is supported at its left end, as viewed in FIGURE 2, from an eccentric shaft 23 and at its right end from an eccentric shaft 24. Supported on the lift plate 22 is an indexing plate 26 which can be rotated with respect to the lift plate about a central axis perpendicular to the lift plate to permit the setting of the helix angle to be formed on the die block 16. During the operation of grinding the indexing plate is locked relative to the lift plate 22 at the desired helix angle.

A cradle 27 is supported on the indexing plate 26 for pivotal movement about a longitudinal axis 28 which is located substantially along the central longitudinal axis of the upper surface of the die block 16. A vertical plane containing the axis 28 intersects a vertical plane in the direction 14 with an angle equal to the helix angle set on the indexing plate 26. The structure of the pivotal mounting of the tipping cradle 27 is described in detail below.

The lifting of the ends of the lift plate 22 is controlled by the rotation of the eccentric shafts 23 and 24. A cam 29 is mounted on the bed frame 10 and is proportioned to engage a cam follower 31 at predetermined points in the reciprocating cycle of the carriage 13 and cause rotation of the eccentric shaft 23 through a crank arm 32. A similar but opposite cam 33 is mounted on the bed frame 10 for engagement by a follower 34 carried by a crank arm 36 to rotate the eccentric shaft 24 in response to axial reciprocation of the carriage 13. The two cams 29 and 33 are adjustable axially with respect to the bed frame 10 in a direction parallel to the direction of reciprocation 14 to provide adjustment of the points in the reciprocating cycle in which the cams are engaged by the associated followers.

The tilting of the cradle 27 is controlled by cams 37 and 38 which are also mounted on the machine bed frame 10 and are engaged by a follower 39 on a crank arm 41 which is in turn mounted on a shaft 42. The earns 37 and 38 are also adjustable along the bed frame 10 and are tiltable to provide adjustment of both the point in the cycle when they are engaged by the follower 39 as well as adjustment of the rate of rotation of the shaft 42 produced as the carriage reciprocates.

The shaft 42 is provided with a crank arm at its inner end which is connected to a lower end of a connecting link 43. The upper end of the connecting link 43 is connected to a pin 44 mounted on a pedestal 46 welded to the tilting cradle 27. The bearings on the ends of the connecting link 43 are self-aligning spherical bearings and a length adjustment screw 47 is provided for leveling purposes.

The support of the lift plate 22 on the base plate 19 can best be understood by referring to FIGURES 4 through 7. A locating pin 48 (illustrated in FIGURE 7) is mounted in the center of the base plate 19 and extends vertically therefrom through a spherical bearing element 49 which is in turn journaled in a spherical retainer 51 locked in the lift plate 22 by a retainer ring 52 and screws 53. The bearing element 49 is free to slide axially along the locating pin 48 and axially positions the lift plate 22 with respect to the base plate 19 while permitting tilting action therebetween.

Axial alignment between the lift plate 22 and the base plate 19 is provided by a pair of rectangular keys 54 and 56 (illustrated in FIGURES 4 and 5). These keys 54 and 56 are bolted to the base plate 19 by bolts 57 and extending into mating axially extending grooves 58 formed in the lift plate 22. The two keys 54 and 56 restrain the lift plate 22 against lateral movement relative to the base plate 19 while permitting tilting or vertical movement of the lift plate 22 with respect to the base plate 19. The keys 54 and 56 do not prevent axial movement between the base plate 19 and the lift plate 22, but this movement is prevented by the locating pin 48 in combination with the spherical bearing 49, 51 (illustrated in FIGURE 7).

The structure of the eccentric shafts 23 and 24 and their support on the base plate 19 as well as their connection to the lift plate 22 are identical, so only one will be described in detail.

Referring to FIGURE 5, the eccentric shaft 24 is journaled in bearings 59 at one end and in a bearing 62 at the other end. The bearings 59 are mounted in a sleeve 61 which is in turn mounted on a pedestal 63 secured to the base plate 19 by bolts 64. The bearing 62 is mounted in a pedestal '66 secured to the base plate 19 by bolts 67. The bearings 59 and 62 are aligned so the eccentric shaft is journaled for rotation about the axis 68.

The eccentric shaft 24 is provided with spaced eccentric bearing portions 69 inwardly from the two pedestals 63 and 66. A first pivot link 71 is journaled on the left bearing portion 69 (as viewed in FIGURE 5) and a second pivot link 72 is journaled on the right eccentric hearing portion 69. The links 71 and 72 are similar and are each pivoted at their lower ends on pivot pins 73 and 74, respectively, which are mounted horizontally in the lift plate 22. Rotation of the eccentric shaft 24 therefore raises or lowers the associated end of the lift plate 22 by an amount which is controlled by the rotation of the eccentric shaft 24. Thus, the rotation of the shaft 24 by the engagement of the follower 34 with the cam 33 controls the vertical movement of the right end of the lift plate 22 (as viewed in FIGURE 2) and rotation of the eccentric shaft 23 by engagement of the follower 31 with the cam 29 controls the vertical position of the left end of the lift plate 22.

An arm 76 is mounted on the eccentric shaft 24 on the rearward end thereof and is provided with a pin 77 connecting with a tension spring 78 which holds the follower 34 against the horizontal surface 79. The action of the cam 33 overcomes the force of the spring 78 and produces rotation of the arm 36 when the right end of the lift plate is to be raised. A similar but opposite spring is provided for the eccentric shaft 23.

A ring bearing 81 (illustrated in FIGURE 7) is mounted in the lift plate 22 around the locating pin 48 and fits into a circular recess 82 in the indexing plate 26 to provide a pivot and to radially locate the indexing plate 26 with respect to the lift plate 22. The structure for controlling the indexing rotation is best illustrated in FIG- URE 3. An indexing screw 83 extends through a pedestal 84 mounted on the lift plate 22 and is axially fixed with respect thereto by a knob 86 on one side and a thrust ring 87 on the other side. The threaded end of the indexing screw is threaded into a threaded fitting 88 journaled on a pin 89 mounted on the indexing plate 26 to rotate about the axis of the ring bearing 81 relative to the lift plate 22. Lock bolts 93 are threaded into projections 94 extending laterally from the lift plate 22 and extend through arcuate slots 92 in projections 91 on the indexing plate 26. After the desired indexed position is reached the lock bolts 93 are tightened to prevent further rotation of the indexing plate 26 relative to the lift plate 22. A gauge pin 96 mounted on the indexing plate 26 extends radially from the indexing axis and cooperates with a fixed pin 97 on the pedestal 84 so that gauge blocks can be used between the two to accurately determine indexed positions.

The mounting of the cradle 27 on the index plate 26 is best illustrated in FIGURES 9 through 12. Similar mounting structures are provided at each end of the indexing plate so only one need be described in detail. A hearing pedestal 101 is bolted to the indexing plate 26 by bolts 102 and provides a support for two similar roller bearings 103 and 104. These bearings engage the lower curved surface 106 of a projection 107 formed as a sector of a cylinder projecting from a plate 108 volted to the tilting cradle 27 by bolts 109.

A central roller 111 on the pedestal 101 engages the upper curved surface 112 of the projection 107 and cooperates with the two rollers 103 and 104 to support the plate 108 and in turn the tipping cradle for pivotal movement about an axis located at the center of curvature of the two curved surfaces 106 and 112. The various elements are proportioned so that this pivot axis 28 is located substantially at the upper surface of a die block 16 supported on the chuck 17 and extends along the central longitudinal axis of the die block 16. Since there are two sets of roller bearings and plates 108 one at each end of the tipping cradle (as illustrated in FIGURE 4) the longitudinal axis 28 is well controlled.

In order to lock the cradle 27 against axial movement relative to the indexing plate 26 a pair of rollers 114 and 115 are provided on each of the bearing pedestals 101 and positioned for engagement with end face 116 on the associated projection 107. Since the end faces 116 are opposed to each other this provides axial locking of the cradle with respect to the indexing plate 26.

The axis of tipping 28 is located along the upper surface of the die block 16 so that tipping of the die block will not result in a lateral displacement of the upper surface thereof. The tipping of the cradle 27 is controlled by the rotation of the shaft 42 and the connecting link 43. A pair of compression springs 117 (illustrated in FIG- URES 3 and 4) create a resilient force tending to raise the rearward side of the cradle 27 to preload the bearings eliminating backlish and also to produce a torque urging the follower 39 downward toward the associated cams. When desired, the tipping cradle 27 can be locked by screwing lock bolts 118 down against projections on the indexing plate 26. The chuck 17 is secured to the upper surface of the tipping cradle 27 by clamps 119 and screws 121.

Referring now to FIGURE 1, the die block 16 prior to the grinding operation is formed with a fiat upper face. As the block is carried under the Wheel 11 by the reciprocation of the carriage 13 thread lands 121 are formed having a profile shaped to mate with an form the desired thread form on the bolt blank to be threaded. The thread lands 121 are inclined relative to the central longitudinal axis of the die block 16 by an angle equal to the required helix angle.

The rectangular section A-A' to B-B' is planar and is normally made long enough to provide at least three turns of the blank being rolled. The portion of the die block 16 between A-A and C-C' is relieved as a smooth curve to provide the roll-on portion of the die. Similarly, the portion from B-B' to D-D' is also relieved in a similar manner to provide a roll-off portion. The section A-A' to C-C' is identical but opposite to the section B-B' to D-D', so either may be used as the roll-on or roll-ofi portion depending upon the way the die is mounted in the thread rolling machine and direction of die movement in such machine.

The various cams operating the lift plate 22 and the tilt cradle 27 are arranged so that as the die block 16 is carried under the wheel 11 by the carriage 13 and supporting fixture 18 the adjacent end of the lift plate 22 is raised and the tilt carriage 27 is tipped to start the relief end. Assuming the first cut is from left to right (as viewed in FIGURES 1 and 2) the wheel 11 will engage the corner C first because of the helix angle. At this point in the stroke the roll 31 is in engagement with the cam 29 and the left end of the lift plate 21 is raised. Also the follower 39 is in engagement with the cam 38 and the cradle 27 is tipped from the horizontal position so that the corner at C is lower than the corner at C. As the wheel 11 moves along the surface of the die block 16 the left end of the lift plate 22 drops down as the follower 31 moves down along the face of the cam 29. At the same time the movement of the follower 39 along the cam 38 results in a tipping or rolling about the axis 28 to raise the corner at C.

The rate of tipping about the axis 28 is synchronized with the rate of lowering of the left end lift plate 22 so that a tooth surface at the ends of the lands 121 is smoothly curved along the relief portion between C-C and A-A' until the line of the wheel contact reaches the point A. At this point in the cycle the near side of the wheel has already passed the point A because of the helix angle. When the lands have been cut along the relief sections at the point A the lift plate 22 is level and the follower 31 is in engagement with the horizontal section '79 extending to the left from the cam 29, so further rotation of the eccentric shaft 23 does not occur. Also at this point in the cycle the follower 34 is still spaced from the cam 33 in engagement with the horizontal section 79. Therefore, the right end of the lift plate does not move vertically during the formation of the relief C-C' to A-A.

When the lands are completed at the point A' all of the followers 31, 34 and 39 move along horizontal sections as the carriage continues to carry the die block 16 along the central section until the lands are formed to the point B, so the central section A-A' to B-B' is planar. When the lands 121 are formed to the point B the cams initiate the formation of the relief B-B' to D-D. At this point in the cycle the follower 34 engages the cam 33 and causes anticlockwise rotation of the eccentric shaft 24 to lift the right end of the lift plate 22. At the same time the follower 39 moves into contact with the cam 37 and commences rotation of the shaft 42 in a clockwise direction causing tilting in an anticlockwise direction about the axis 28 as viewed from the left in FIGURE 1. The cams are proportioned so that the point B raises while the point B remains at the same height. The lowering of the point B created by the tilting equals and cancels the raising of the right end of the lift plate 22. Therefore, the point B remains at the same height with respect to the wheel until the wheel reaches B. As the wheel passes B the cams raise both B and B as continued movement occurs.

As the carriage continues to move to the left the raising of the right end of the lift plate 22 and the simultaneous tilting of the cradle 27 continues until the wheel completes the lands at the point D'. At this point in the cycle the first pass is complete and the lands 121 including the relief at both ends of the die block 16 are rough formed. The carriage travel is then reversed and a second cut is made back under the wheel 11. This back and forth cutting with appropriate grinding wheel adjustments is continued until the desired finish and accuracy is achieved. The action of the cams on the backstroke is reversed so the backstroke results in a complete duplication of the movements occurring in the forward stroke.

The tilting of the die block 16 is necessary since the die block is carried under the wheel at an angle equal to the helix angle and if the die block were not tilted during the cutting of the relief as the adjacent end of the die raises, the relief section would be normal to the lands rather than normal to the longitudinal axis of the die and as a result blanks rolling along the roll-on or roll-off portion would be canted. This would cause distortion of the threads and produce difiiculties in the thread rolling operation. However, by timed tilting of the block as it is raised or lowered the line between B-B' and between A-A' is substantially perpendicular to the longitudinal axis of the block 16 and inclined with respect to the lands 121.

When die blocks of the opposite hand of thread, for example lefthand or righthand, are required it is necessary to reverse the cams 37 and 38 so that the tilting occurs in the opposite direction.

The axis 28 of tilting is located substantially at the upper surface of the die block 16 so that there is no lateral shifting of the die block during the tilting. For example, if the tilting axis 28 were located either above or below the upper surface of the die block any substantial distance the tilting would result in a lateral shifting and would produce a hook on the ends of the lands. The tilting axis 28 is located along the longitudinal center line of the upper surface of the die block so that lateral shifting does not occur and so that the raising and lowering created by tilting is symmetrical with respect to the longitudinal center line of the die block.

With a machine incorporating this invention it is possible for relatively unskilled labor to manufacture high quality very accurate tooth lands on the die blocks and variations between one die block and the next are substantially non-existant. Once the machine is set up with the cams properly positioned and the helix angle properly set the operator merely has to place the die block in the proper position of the chuck and cycle the machine through the necessary strokes to complete a finished die block. Also, the hand grinding and hand filing of the relief sections which have previously been require-d is eliminated.

Although a preferred embodiment of this invention is illustrate-d, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention as defined in the following claims.

I claim:

1. A fixture for supporting work pieces for contour forming comprising a base adapted to be mounted on a reciprocating carriage of a machine tool, a cradle adapted to support a work piece, and an operating assembly connecting said cradle and said base, said operating assembly including first cam operated means operable to move said cradle in a direction normal to said base in response to reciprocation of said carriage, and second cam operate-d means operable to laterally tip said cradle in timed relation to the operation of said first cam operated means.

2. A fixture for supporting work pieces for contour forming comprising a base adapted to be mounted on a reciprocating carriage of a machine tool, a cradle adapted to support a work piece, and an operating assembly connecting said cradle and said base, said operating assembly including first cam operated means operable to move said cradle in a direction substantially normal to said base in response to reciprocation of said carriage, second cam operated means operable to laterally tip said cradle in timed relation to the operation of said first cam operated means, and indexing means providing adjustment of said cradle about an indexing axis substantially normal to said base.

3. A fixture for supporting thread rolling die blocks during grinding comprising a base adapted to be mounted on a reciprocating carriage of a grinder, a chuck adapted to support a die block for grinding, and a support assembly connecting said chuck and said base, said support assembly including first cam operated means operable to move said chuck in a direction substantially normal to said base in response to reciprocation of said carriage, second cam operated means operable to laterally tip said chuck about a longitudinal axis in timed relation to the operation of said first cam operated means, and indexing means providing adjustment of said chuck about an indexing axis substantially normal to said base.

4. A fixture adapted to be mounted on the reciprocating carriage of a machine tool comprising a base, a plate adapted to support a work holder, and a support assembly supporting said plate from said base, said support assembly including first means operable to separately move the ends of said plate substantially normal with respect to said base, and second means operable to tip said plate about a longitudinal axis, said means operating in timed relation to each other to provide a predetermined pattern of movement of said plate with respect to said base.

5. A fixture adapted to be mounted on the reciprocat ing carriage of a machine tool comprising a base, a plate adapted to support a work holder, and a support assembly supporting said plate from said base, said support assembly including first means operable to separately move the ends of said plate substantially normal with respect to said base, second means operable to index said plate around an axis substantially normal to said base, and third means operable to tip said plate about a longitudinal axis, said first and third means operating in timed relation to each other to provide a predetermined pattern of movement of said plate with respect to said base.

6. A work holder comprising an elongated base, a lift plate, a pair of eccentric shafts journaled on said base, links connecting said shafts and the ends of said lift plate operable to move the ends of said lift plate with respect to said base in response to rotation of said eccentric shafts, means restraining said lift plate against longitudinal movement relative to said base, and a cradle supported by said lift plate and journaled for tipping movement about a longitudinal axis above said cradle.

7. A work holder comprising a frame, an elongated base reciprocable relative to said frame, a lift plate, a pair of eccentric shafts journaled on said base, links connecting said shafts and the ends of said lift plate operable to move the ends of said lift plate with respect to said base in response to rotation of said eccentric shafts, first cam means on said frame causing rotation of said shafts in response to reciprocation of said base, means restraining said lift plate against longitudinal movement relative to said base, a cradle supported by said lift plate and journaled for tipping movement about a longitudinal axis, and second cam means on said frame causing tipping movement of said cradle in response to reciprocation of said base.

8. A work holder comprising an elongated base, a lift plate, a pair of eccentric shafts journaled on said base, links connecting said shafts and the ends of said lift plate operable to move the ends of said lift plate with respect to said base in response to rotation of said eccentric shafts, means restraining said lift plate against longitudinal movement relative to said base, an indexing plate journaled on said lift plate for indexing rotation about an axis normal to said lift plate, and a cradle journaled on said indexing plate for tipping movement about an axis above said cradle.

9. A work holder comprising an elongated base, a lift plate, a pair of eccentric shafts journaled on said base, links connecting said shafts and the ends of said lift plate operable to move the ends of said lift plate with respect to said base in response to rotation of said eccentric shafts, means restraining said lift plate against longitudinal movement relative to said base, an indexing plate journaled on said lift plate for indexing rotation about an axis normal to said lift plate, a cradle, bearing means supporting said cradle for pivotal movement with respect to said indexing plate about an axis spaced above said cradle, said bearing means including spaced supports formed with similar and opposed arcurate bearing surfaces and opposed rollers movable along said opposed bearing surfaces.

10. A work holder comprising an elongated base, a lift plate, support means connecting said lift plate and base operable to move said lift plate in a direction substantially normal to said base, a cradle, bearing means supporting said cradle for pivotal movement with respect to said lift plate about an axis spaced above said cradle, said bearing means including spaced supports formed with similar and opposed arcuate bearing surfaces and opposed rollers movable along opposed bearing surfaces.

11. A Work holder comprising a reciprocating elongated base, a lift plate, first cam operated means connecting said lift plate and base operable in response to reciprocation of said base to move said lift plate in a direction substantially normal to said base, a cradle, bearing means supporting said cradle for pivotal movement with respect to said lift plate about an axis spaced above said cradle, said bearing means including spaced supports formed with similar and opposed arcuate bearing surfaces and opposed rollers movable along opposed bearing surfaces, and second cam means connected between said cradle and base producing pivotal movement of said cradle in response to reciprocation of the said base.

References Cited UNITED STATES PATENTS 1,891,279 12/1932 Hauk 51100 2,136,491 11/1938 Cornell 51-234 2,457,383 12/1948 Kraift 5l-94 2,569,005 9/1951 Kindling 5194 2,688,212 9/1954 Dyer 51-94 2,776,528 1/1957 Niederer 51234 LESTER M. SWINGLE, Primary Examiner.

D. G. KELLY, Assistant Examiner.

U.S. Cl. X.R. 

